cpuidle: calxeda: add cpu_pm_enter/exit calls

Wnen powergating the core, we need to call cpu pm notifiers to save VFP
state (!SMP only) and resetting the breakpoint h/w.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-pm@vger.kernel.org